Lettuce cultivar palermo

ABSTRACT

A lettuce cultivar, designated Palermo, is disclosed. The invention relates to the seeds, plants and plant parts of lettuce cultivar Palermo and to methods for producing a lettuce plant by crossing the cultivar Palermo with itself or another lettuce cultivar. The invention further relates to methods for producing a lettuce plant containing in its genetic material one or more transgenes and to the transgenic lettuce plants and plant parts produced by those methods. This invention also relates to lettuce cultivars or breeding cultivars and plant parts derived from lettuce cultivar Palermo, to methods for producing other lettuce cultivars, lines or plant parts derived from lettuce cultivar Palermo and to the lettuce plants, varieties, and their parts derived from the use of those methods. The invention further relates to hybrid lettuce seeds, plants, and plant parts produced by crossing cultivar Palermo with another lettuce cultivar.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. provisionalpatent application Ser. No. 61/776,148 filed on Mar. 11, 2013, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a new green leaf lettuce (Lactucasativa L.) variety designated Palermo, which exhibits tan seed color.All publications cited in this application are herein incorporated byreference.

There are numerous steps in the development of any novel, desirableplant germplasm. Plant breeding begins with the analysis and definitionof problems and weaknesses of the current germplasm, the establishmentof program goals, and the definition of specific breeding objectives.The next step is selection of germplasm that possess the traits to meetthe program goals. The goal is to combine in a single variety or hybridan improved combination of desirable traits from the parental germplasm.These important traits may include increased head size and weight,higher seed yield, improved color, resistance to diseases and insects,tolerance to drought and heat, and better agronomic quality.

Practically speaking, all cultivated forms of lettuce belong to thehighly polymorphic species Lactuca sativa that is grown for its ediblehead and leaves. As a crop, lettuce is grown commercially whereverenvironmental conditions permit the production of an economically viableyield. Lettuce is the world's most popular salad. In the United States,the principal growing regions are California and Arizona which produceapproximately 329,700 acres out of a total annual acreage of more than333,300 acres (USDA 2005). Fresh lettuce is available in the UnitedStates year-round although the greatest supply is from May throughOctober. For planting purposes, the lettuce season is typically dividedinto three categories (i.e., early, mid, and late), with the coastalareas planting from January to August, and the desert regions plantingfrom August to December. Fresh lettuce is consumed nearly exclusively asfresh, raw product and occasionally as a cooked vegetable.

Lactuca sativa is in the Cichoreae tribe of the Asteraceae (Compositae)family. Lettuce is related to chicory, sunflower, aster, dandelion,artichoke, and chrysanthemum. L. sativa is one of about 300 species inthe genus Lactuca. There are seven different morphological types oflettuce. The crisphead group includes the iceberg and batavian types.Iceberg lettuce has a large, firm head with a crisp texture and a whiteor creamy yellow interior. The batavian lettuce predates the icebergtype and has a smaller and less firm head. The butterhead group has asmall, soft head with an almost oily texture. The romaine, also known ascos lettuce, has elongated upright leaves forming a loose, loaf-shapedhead and the outer leaves are usually dark green. Leaf lettuce comes inmany varieties, none of which form a head, and include the green oakleaf variety. Latin lettuce looks like a cross between romaine andbutterhead. Stem lettuce has long, narrow leaves and thick, ediblestems. Oilseed lettuce is a type grown for its large seeds that arepressed to obtain oil. Latin lettuce, stem lettuce, and oilseed lettuceare seldom seen in the United States.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon a reading of the specification.

SUMMARY OF THE INVENTION

The following embodiments and aspects thereof are described inconjunction with systems, tools, and methods which are meant to beexemplary and illustrative, not limiting in scope. In variousembodiments, one or more of the above-described problems have beenreduced or eliminated, while other embodiments are directed to otherimprovements.

According to the invention, there is provided a novel lettuce cultivardesignated Palermo. This invention thus relates to the seeds of lettucecultivar Palermo, to the plants of lettuce cultivar Palermo, and tomethods for producing a lettuce plant produced by crossing the lettucecultivar Palermo with itself or another lettuce plant, to methods forproducing a lettuce plant containing in its genetic material one or moretransgenes, and to the transgenic lettuce plants produced by thatmethod. This invention also relates to methods for producing otherlettuce cultivars derived from lettuce cultivar Palermo and to thelettuce cultivar derived by the use of those methods. This inventionfurther relates to hybrid lettuce seeds and plants produced by crossinglettuce cultivar Palermo with another lettuce variety.

In another aspect, the present invention provides regenerable cells foruse in tissue culture of lettuce cultivar Palermo. The tissue culturewill preferably be capable of regenerating plants having essentially allof the physiological and morphological characteristics of the foregoinglettuce plant, and of regenerating plants having substantially the samegenotype as the foregoing lettuce plant. Preferably, the regenerablecells in such tissue cultures will be callus, protoplasts, meristematiccells, cotyledons, hypocotyl, leaves, pollen, embryos, roots, root tips,anthers, pistils, shoots, stems, petiole flowers, and seeds. Stillfurther, the present invention provides lettuce plants regenerated fromthe tissue cultures of the invention.

Another aspect of the invention is to provide methods for producingother lettuce plants derived from lettuce cultivar Palermo. Lettucecultivars derived by the use of those methods are also part of theinvention.

The invention also relates to methods for producing a lettuce plantcontaining in its genetic material one or more transgenes and to thetransgenic lettuce plant produced by those methods.

In another aspect, the present invention provides for single geneconverted plants of Palermo. The single transferred gene may preferablybe a dominant or recessive allele. Preferably, the single transferredgene will confer such traits as male sterility, herbicide resistance,insect or pest resistance, modified fatty acid metabolism, modifiedcarbohydrate metabolism, resistance for bacterial, fungal, or viraldisease, male fertility, enhanced nutritional quality, and industrialusage. The single gene may be a naturally occurring lettuce gene or atransgene introduced through genetic engineering techniques.

The invention further provides methods for developing lettuce plants ina lettuce plant breeding program using plant breeding techniquesincluding recurrent selection, backcrossing, pedigree breeding,restriction fragment length polymorphism enhanced selection, geneticmarker enhanced selection, and transformation. Seeds, lettuce plants,and parts thereof, produced by such breeding methods are also part ofthe invention.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference bystudy of the following descriptions.

DETAILED DESCRIPTION OF THE INVENTION

In the description and tables which follow, a number of terms are used.In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided:

Allele. The allele is any of one or more alternative forms of a gene,all of which relate to one trait or characteristic. In a diploid cell ororganism, the two alleles of a given gene occupy corresponding loci on apair of homologous chromosomes.

Backcrossing. Backcrossing is a process in which a breeder repeatedlycrosses hybrid progeny back to one of the parents, for example, a firstgeneration hybrid F₁ with one of the parental genotype of the F₁ hybrid.

Big Vein virus. Big vein is a disease of lettuce caused by LettuceMirafiori Big Vein Virus which is transmitted by the fungus Olpidiumvirulentus, with vein clearing and leaf shrinkage resulting in plants ofpoor quality and reduced marketable value.

Bolting. The premature development of a flowering stalk, and subsequentseed, before a plant produces a food crop. Bolting is typically causedby late planting when temperatures are low enough to cause vernalizationof the plants.

Bremia lactucae. An Oomycete that causes downy mildew in lettuce incooler growing regions.

Core diameter. The diameter of the lettuce stem at the base of the cuthead.

Core length. Length of the internal lettuce stem measured from the baseof the cut and trimmed head to the tip of the stem.

Corky root. A disease caused by the bacterium Rhizomonas suberifaciens,which causes the entire taproot to become brown, severely cracked, andnon-functional.

Cotyledon. One of the first leaves of the embryo of a seed plant;typically one or more in monocotyledons, two in dicotyledons, and two ormore in gymnosperms.

Essentially all the physiological and morphological characteristics. Aplant having essentially all the physiological and morphologicalcharacteristics means a plant having the physiological and morphologicalcharacteristics of the recurrent parent, except for the characteristicsderived from the converted gene.

First water date. The date the seed first receives adequate moisture togerminate. This can and often does equal the planting date.

Frame diameter. The frame diameter is a measurement of the lettuce plantdiameter at its widest point, measured from the outer most wrapper leaftip to the outer most wrapper leaf tip.

Gene. As used herein, “gene” refers to a segment of nucleic acid. A genecan be introduced into a genome of a species, whether from a differentspecies or from the same species, using transformation or variousbreeding methods.

Green leaf lettuce. A type of lettuce characterized by having curled orincised leaves forming a loose green rosette that does not develop intoa compact head.

Head diameter. Diameter of the cut and trimmed head, sliced vertically,and measured at the widest point perpendicular to the stem.

Head height. Height of the cut and trimmed head, sliced vertically, andmeasured from the base of the cut stem to the cap leaf.

Head weight. Weight of saleable lettuce head, cut and trimmed to marketspecifications.

Lettuce Mosaic virus. A disease that can cause a stunted, deformed, ormottled pattern in young lettuce and yellow, twisted, and deformedleaves in older lettuce.

Lettuce necrotic stunt virus (LNSV). A disease of lettuce that can causeseverely stunted plants having yellowed outer leaves and brown, necroticspotting. LNSV is a soilborne pathogen with no known vector.

Market stage. Market stage is the stage when a lettuce plant is readyfor commercial lettuce harvest. In the case of an iceberg variety, thehead is solid, and has reached an adequate size and weight.

Maturity date. Maturity refers to the stage when the plants are of fullsize or optimum weight, in marketable form or shape to be of commercialor economic value.

Nasonovia ribisnigri. A lettuce aphid that colonizes the innermostleaves of the lettuce plant, contaminating areas that cannot be treatedeasily with insecticides.

Plant. “Plant” includes plant cells, plant protoplasts, plant cells oftissue culture from which lettuce plants can be regenerated, plantcalli, plant clumps and plant cells that are intact in plants, or partsof plants such as pollen, flowers, seeds, leaves, stems and the like.

Quantitative Trait Loci. Quantitative Trait Loci (QTL) refers to geneticloci that control to some degree, numerically representable traits thatare usually continuously distributed.

Ratio of head height/diameter. Head height divided by the head diameteris an indication of the head shape; <1 is flattened, 1=round, and >1 ispointed.

Regeneration. Regeneration refers to the development of a plant fromtissue culture.

RHS. RHS refers to the Royal Horticultural Society of England whichpublishes an official botanical color chart quantitatively identifyingcolors according to a defined numbering system. The chart may bepurchased from Royal Horticulture Society Enterprise Ltd., RHS Garden;Wisley, Woking; Surrey GU236QB, UK.

Rogueing. Rogueing is the process in seed production where undesiredplants are removed from a variety. The plants are removed since theydiffer physically from the general desired expressed characteristics ofthe variety. The differences can be related to size, color, maturity,leaf texture, leaf margins, growth habit, or any other characteristicthat distinguishes the plant.

Single gene converted. Single gene converted or conversion plant refersto plants which are developed by a plant breeding technique calledbackcrossing or via genetic engineering wherein essentially all of thedesired morphological and physiological characteristics of a line arerecovered in addition to the single gene transferred into the line viathe backcrossing technique or via genetic engineering.

Tip burn. Means a browning of the edges or tips of lettuce leaves thatis a physiological response to a lack of calcium.

Tomato Bushy Stunt. A disease which causes stunting of growth, leafmottling, and deformed or absent fruit.

VSTMA1. Refers to the mutant allele present in Palermo which confers tanseed color. A representative sample of said mutant allele has beendeposited under ATCC Accession number PTA-120671.

The following detailed description is of the currently contemplatedmodes of carrying out the invention. The description is not to be takenin a limiting sense, but is made merely for the purpose of illustratingthe general principles of the invention, since the scope of theinvention is best defined by the appended claims.

Broadly, the present invention is directed toward green leaf lettucevarieties containing mutant allele VSTMA1 that exhibit tan seed color,including both plants and seeds. Specifically, the green leaf lettucevariety of the present invention, Palermo, exhibits tan seed color. Todate, there are no known green leaf lettuce varieties with tan seedcolor that are adapted for the U.S. market. The green leaf lettucevariety exemplified in the present invention, Palermo, is thus differentfrom known varieties of green leaf lettuce. Lettuce cultivar Palermo isa green leaf lettuce variety suitable for carton, whole leaf andprocessing production in the Western United States. Specifically,Palermo is adapted to the summer season in the Salinas Valley,California, and the fall and spring seasons in the Imperial Valley,California and Yuma, Ariz. Additionally, lettuce cultivar Palermo isresistant to corky root infection and tip burn.

The unique trait of tan seed color exhibited by lettuce cultivar Palermoof the present invention is conferred by a mutant allele designatedVSTMA1. The allele may be a single genetic mutation, a single mutationwith modifier genes, dominant, partially dominant or recessive allele.The allele conferring the unique trait of the present invention may belinked or isolated. Based on the genetics of inheritance of seed color,mutant allele VSTMA1 of the present invention is believed to be a singlerecessive mutation. The tan seed color mutant was surprisinglydiscovered from a black seeded leaf lettuce variety and did notsegregate for seed color upon subsequent selfing; however, when the tanseed color mutant was crossed, seed color segregation was seen in theprogeny and the tan seed color has been introgressed into several othernew lettuce cultivars. Additional genetic and molecular testing willdetermine the mutant allele(s) of the present invention.

The cultivar Palermo has shown uniformity and stability for the traits,within the limits of environmental influence for the traits. It has beenself-pollinated a sufficient number of generations with carefulattention to uniformity of plant type. The line has been increased withcontinued observation for uniformity. No variant traits have beenobserved or are expected in cultivar Palermo.

Lettuce cultivar Palermo has the following morphological andphysiological characteristics described in Table 1.

TABLE 1 VARIETY DESCRIPTION INFORMATION Plant: Type: Green leaf lettuceSeed: Color: Range from RHS 199A, 199B, 199C (Tan) Light dormancy:Present Heat dormancy: Present Cotyledon (to fourth leaf stage): Shapeof fourth leaf: Spatulate Length/width index of 4^(th) leaf (L/W × 10):15.48 Apex: Rounded Base: Narrow Undulation: Slight Green color: RHS141A (Dark green) Anthocyanin distribution: Absent Rolling: AbsentCupping: Absent Reflexing: Absent Mature Leaves: Margin: Moderatelyserrated Incision depth: Shallow Indentation: Slight Undulation of theapical margin: Slight Green color (at harvest maturity): Dark greenAnthocyanin distribution: Absent Size: Medium (5″ × 5″) Glossiness: DullBlistering: Slight Thickness: Thick Trichomes: Absent Plant (at marketstage): Spread of frame leaves: 30.0 cm Head shape: Open/non-headingHead size class: Medium Head weight: 363.0 g Head firmness: Loose Butt:Shape: Flat Midrib: Slight protrusion Core: Core height from base ofhead to apex: 1.5 inches Bolting: First water date: Apr. 13, 2013 (inCorcoran, California) Number of days from first water date to seed stalkemergence: 63 days Time of beginning of bolting: Jun. 15, 2013 Date offirst flower: Jul. 8, 2013 Height of mature seed stalk: 43.0 inchesBolter leaf margin: Serrated Bolter leaf color: Dark green Bolter habit:Terminal inflorescence: Present Lateral shoots: Absent Basal sideshoots: Absent Primary Regions of Adaptation: Spring area: Desertsouthwest Summer area: California coast Autumn area: Desert southwestWinter area: Not adapted Disease/Pest Resistance: Corky root rot(Rhizomonas suberifaciens): Resistant Lettuce necrotic stunt virus(LNSV): Susceptible Sclerotinia: Moderately resistant Nasonoviaribisnigri: Susceptible to Nr0 and Nr1 Physiological Responses: Tipburn: Highly resistant Cold weather heading: Susceptible

FURTHER EMBODIMENTS OF THE INVENTION

Lettuce in general, and green leaf lettuce in particular, is animportant and valuable vegetable crop. Thus, a continuing goal oflettuce plant breeders is to develop stable, high yielding lettucecultivars that are agronomically sound. To accomplish this goal, thelettuce breeder must select and develop lettuce plants with traits thatresult in superior cultivars.

Proper testing should detect any major faults and establish the level ofsuperiority or improvement over current cultivars. In addition toshowing superior performance, there must be a demand for a new cultivarthat is compatible with industry standards or which creates a newmarket. The introduction of a new cultivar will incur additional coststo the seed producer, the grower, processor and consumer for specialadvertising and marketing, altered seed and commercial productionpractices, and new product utilization. The testing preceding release ofa new cultivar should take into consideration research and developmentcosts, as well as technical superiority of the final cultivar. Forseed-propagated cultivars, it must be feasible to produce seed easilyand economically.

Choice of breeding or selection methods depends on the mode of plantreproduction, the heritability of the trait(s) being improved, and thetype of cultivar used commercially (e.g., F₁ hybrid cultivar, purelinecultivar, etc.). For highly heritable traits, a choice of superiorindividual plants evaluated at a single location will be effective,whereas for traits with low heritability, selection should be based onmean values obtained from replicated evaluations of families of relatedplants. Popular selection methods commonly include pedigree selection,modified pedigree selection, mass selection, and recurrent selection.

The complexity of inheritance influences choice of the breeding method.Backcross breeding is used to transfer one or a few favorable genes fora highly heritable trait into a desirable cultivar. This approach hasbeen used extensively for breeding disease-resistant cultivars. Variousrecurrent selection techniques are used to improve quantitativelyinherited traits controlled by numerous genes. The use of recurrentselection in self-pollinating crops depends on the ease of pollination,the frequency of successful hybrids from each pollination, and thenumber of hybrid offspring from each successful cross.

Each breeding program should include a periodic, objective evaluation ofthe efficiency of the breeding procedure. Evaluation criteria varydepending on the goal and objectives, but should include gain fromselection per year based on comparisons to an appropriate standard, theoverall value of the advanced breeding lines, and the number ofsuccessful cultivars produced per unit of input (e.g., per year, perdollar expended, etc.).

Promising advanced breeding lines are thoroughly tested and compared toappropriate standards in environments representative of the commercialtarget area(s) for at least three years. The best lines are candidatesfor new commercial cultivars. Those still deficient in a few traits areused as parents to produce new populations for further selection.

These processes, which lead to the final step of marketing anddistribution, usually take from ten to twenty years from the time thefirst cross or selection is made. Therefore, development of newcultivars is a time-consuming process that requires precise forwardplanning, efficient use of resources, and a minimum of changes indirection.

A most difficult task is the identification of individuals that aregenetically superior, because for most traits the true genotypic valueis masked by other confounding plant traits or environmental factors.One method of identifying a superior plant is to observe its performancerelative to other experimental plants and to a widely grown standardcultivar. If a single observation is inconclusive, replicatedobservations provide a better estimate of its genetic worth.

The goal of lettuce plant breeding is to develop new, unique, andsuperior lettuce cultivars. The breeder initially selects and crossestwo or more parental lines, followed by repeated selfing and selection,producing many new genetic combinations. The breeder can theoreticallygenerate billions of different genetic combinations via crossing,selfing, and mutations. The breeder has no direct control at thecellular level. Therefore, two breeders will never develop the sameline, or even very similar lines, having the same lettuce traits.

Each year, the plant breeder selects the germplasm to advance to thenext generation. This germplasm is grown under different geographical,climatic, and soil conditions, and further selections are then madeduring, and at the end of, the growing season. The cultivars that aredeveloped are unpredictable. This unpredictability is because thebreeder's selection occurs in unique environments, with no control atthe DNA level (using conventional breeding procedures), and withmillions of different possible genetic combinations being generated. Abreeder of ordinary skill in the art cannot predict the final resultinglines he develops, except possibly in a very gross and general fashion.The same breeder cannot produce the same line twice by using the exactsame original parents and the same selection techniques. Thisunpredictability results in the expenditure of large research monies todevelop superior lettuce cultivars.

The development of commercial lettuce cultivars requires the developmentof lettuce varieties, the crossing of these varieties, and theevaluation of the crosses. Pedigree breeding and recurrent selectionbreeding methods are used to develop cultivars from breedingpopulations. Breeding programs combine desirable traits from two or morevarieties or various broad-based sources into breeding pools from whichcultivars are developed by selfing and selection of desired phenotypes.The new cultivars are crossed with other varieties and the hybrids fromthese crosses are evaluated to determine which have commercialpotential.

Pedigree breeding is used commonly for the improvement ofself-pollinating crops or inbred lines of cross-pollinating crops. Twoparents which possess favorable, complementary traits are crossed toproduce an F₁. An F₂ population is produced by selfing one or severalF₁'s or by intercrossing two F₁'s (sib mating). Selection of the bestindividuals is usually begun in the F₂ population. Then, beginning inthe F₃, the best individuals in the best families are selected.Replicated testing of families, or hybrid combinations involvingindividuals of these families, often follows in the F₄ generation toimprove the effectiveness of selection for traits with low heritability.At an advanced stage of inbreeding (i.e., F₆ and F₇), the best lines ormixtures of phenotypically similar lines are tested for potentialrelease as new cultivars.

Mass and recurrent selections can be used to improve populations ofeither self- or cross-pollinating crops. A genetically variablepopulation of heterozygous individuals is either identified or createdby intercrossing several different parents. The best plants are selectedbased on individual superiority, outstanding progeny, or excellentcombining ability. The selected plants are intercrossed to produce a newpopulation in which further cycles of selection are continued.

Backcross breeding has been used to transfer genes for a simplyinherited, highly heritable trait into a desirable homozygous cultivaror line that is the recurrent parent. The source of the trait to betransferred is called the donor parent. The resulting plant is expectedto have the attributes of the recurrent parent (e.g., cultivar) and thedesirable trait transferred from the donor parent. After the initialcross, individuals possessing the phenotype of the donor parent areselected and repeatedly crossed (backcrossed) to the recurrent parent.The resulting plant is expected to have the attributes of the recurrentparent (e.g., cultivar) and the desirable trait transferred from thedonor parent.

The single-seed descent procedure in the strict sense refers to plantinga segregating population, harvesting a sample of one seed per plant, andusing the one-seed sample to plant the next generation. When thepopulation has been advanced from the F₂ to the desired level ofinbreeding, the plants from which lines are derived will each trace todifferent F₂ individuals. The number of plants in a population declineswith each generation due to failure of some seeds to germinate or someplants to produce at least one seed. As a result, not all of the F₂plants originally sampled in the population will be represented by aprogeny when generation advance is completed.

In addition to phenotypic observations, the genotype of a plant can alsobe examined. There are many laboratory-based techniques available forthe analysis, comparison and characterization of plant genotype; amongthese are Isozyme Electrophoresis, Restriction Fragment LengthPolymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs),Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA AmplificationFingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs),Amplified Fragment Length polymorphisms (AFLPs), Simple Sequence Repeats(SSRs—which are also referred to as Microsatellites), and SingleNucleotide Polymorphisms (SNPs).

Isozyme Electrophoresis and RFLPs have been widely used to determinegenetic composition. Shoemaker and Olsen (Molecular Linkage Map ofSoybean (Glycine max), pp. 6.131-6.138 in S. J. O'Brien (ed.) GeneticMaps: Locus Maps of Complex Genomes, Cold Spring Harbor LaboratoryPress, Cold Spring Harbor, N.Y. (1993)) developed a molecular geneticlinkage map that consisted of 25 linkage groups with about 365 RFLP, 11RAPD, three classical markers, and four isozyme loci. See also,Shoemaker, R. C., RFLP Map of Soybean, pp. 299-309, in Phillips, R. L.and Vasil, I. K. (eds.), DNA-Based Markers in Plants, Kluwer AcademicPress, Dordrecht, the Netherlands (1994).

SSR technology is currently the most efficient and practical markertechnology; more marker loci can be routinely used and more alleles permarker locus can be found using SSRs in comparison to RFLPs. Forexample, Diwan and Cregan described a highly polymorphic microsatellitelocus in soybean with as many as 26 alleles. Diwan, N. and Cregan, P.B., Theor. Appl. Genet., 95:22-225 (1997). SNPs may also be used toidentify the unique genetic composition of the invention and progenyvarieties retaining that unique genetic composition. Various molecularmarker techniques may be used in combination to enhance overallresolution.

Molecular markers, which include markers identified through the use oftechniques such as Isozyme Electrophoresis, RFLPs, RAPDs, AP-PCR, DAF,SCARs, AFLPs, SSRs, and SNPs, may be used in plant breeding. One use ofmolecular markers is Quantitative Trait Loci (QTL) mapping. QTL mappingis the use of markers which are known to be closely linked to allelesthat have measurable effects on a quantitative trait. Selection in thebreeding process is based upon the accumulation of markers linked to thepositive effecting alleles and/or the elimination of the markers linkedto the negative effecting alleles from the plant's genome.

Molecular markers can also be used during the breeding process for theselection of qualitative traits. For example, markers closely linked toalleles or markers containing sequences within the actual alleles ofinterest can be used to select plants that contain the alleles ofinterest during a backcrossing breeding program. The markers can also beused to select toward the genome of the recurrent parent and against themarkers of the donor parent. This procedure attempts to minimize theamount of genome from the donor parent that remains in the selectedplants. It can also be used to reduce the number of crosses back to therecurrent parent needed in a backcrossing program. The use of molecularmarkers in the selection process is often called genetic marker enhancedselection or marker-assisted selection. Molecular markers may also beused to identify and exclude certain sources of germplasm as parentalvarieties or ancestors of a plant by providing a means of trackinggenetic profiles through crosses.

Mutation breeding is another method of introducing new traits intolettuce varieties. Mutations that occur spontaneously or areartificially induced can be useful sources of variability for a plantbreeder. The goal of artificial mutagenesis is to increase the rate ofmutation for a desired characteristic. Mutation rates can be increasedby many different means including temperature, long-term seed storage,tissue culture conditions, radiation (such as X-rays, Gamma rays,neutrons, Beta radiation, or ultraviolet radiation), chemical mutagens(such as base analogs like 5-bromo-uracil), antibiotics, alkylatingagents (such as sulfur mustards, nitrogen mustards, epoxides,ethyleneamines, sulfates, sulfonates, sulfones, or lactones), azide,hydroxylamine, nitrous acid, or acridines. Once a desired trait isobserved through mutagenesis the trait may then be incorporated intoexisting germplasm by traditional breeding techniques. Details ofmutation breeding can be found in Principles of Cultivar Development byFehr, Macmillan Publishing Company (1993).

The production of double haploids can also be used for the developmentof homozygous varieties in a breeding program. Double haploids areproduced by the doubling of a set of chromosomes from a heterozygousplant to produce a completely homozygous individual. For example, seeWan, et al., Theor. Appl. Genet., 77:889-892 (1989).

Descriptions of other breeding methods that are commonly used fordifferent traits and crops can be found in one of several referencebooks (e.g., Principles of Plant Breeding, John Wiley and Son, pp.115-161 (1960); Allard (1960); Simmonds (1979); Sneep, et al. (1979);Fehr (1987); “Carrots and Related Vegetable Umbelliferae,” Rubatzky, V.E., et al. (1999).

With the advent of molecular biological techniques that have allowed theisolation and characterization of genes that encode specific proteinproducts, scientists in the field of plant biology developed a stronginterest in engineering the genome of plants to contain and expressforeign genes, or additional, or modified versions of native, orendogenous, genes (perhaps driven by different promoters) in order toalter the traits of a plant in a specific manner. Any DNA sequences,whether from a different species or from the same species, which areintroduced into the genome using transformation or various breedingmethods, are referred to herein collectively as “transgenes.” Over thelast fifteen to twenty years, several methods for producing transgenicplants have been developed, and the present invention, in particularembodiments, also relates to transformed versions of the claimed line.

Nucleic acids or polynucleotides refer to RNA or DNA that is linear orbranched, single or double stranded, or a hybrid thereof. The term alsoencompasses RNA/DNA hybrids. These terms also encompass untranslatedsequence located at both the 3′ and 5′ ends of the coding region of thegene: at least about 1000 nucleotides of sequence upstream from the 5′end of the coding region and at least about 200 nucleotides of sequencedownstream from the 3′ end of the coding region of the gene. Less commonbases, such as inosine, 5-methylcytosine, 6-methyladenine, hypoxanthine,and others can also be used for antisense, dsRNA, and ribozyme pairing.For example, polynucleotides that contain C-5 propyne analogues ofuridine and cytidine have been shown to bind RNA with high affinity andto be potent antisense inhibitors of gene expression. Othermodifications, such as modification to the phosphodiester backbone, orthe 2′-hydroxy in the ribose sugar group of the RNA can also be made.The antisense polynucleotides and ribozymes can consist entirely ofribonucleotides, or can contain mixed ribonucleotides anddeoxyribonucleotides. The polynucleotides of the invention may beproduced by any means, including genomic preparations, cDNApreparations, in vitro synthesis, RT-PCR, and in vitro or in vivotranscription.

Plant transformation involves the construction of an expression vectorthat will function in plant cells. Such a vector comprises DNAcomprising a gene under control of, or operatively linked to, aregulatory element (for example, a promoter). The expression vector maycontain one or more such operably linked gene/regulatory elementcombinations. The vector(s) may be in the form of a plasmid, and can beused alone or in combination with other plasmids, to provide transformedlettuce plants using transformation methods as described below toincorporate transgenes into the genetic material of the lettuceplant(s).

Expression Vectors for Lettuce Transformation: Marker Genes

Expression vectors include at least one genetic marker, operably linkedto a regulatory element (for example, a promoter) that allowstransformed cells containing the marker to be either recovered bynegative selection, i.e., inhibiting growth of cells that do not containthe selectable marker gene, or by positive selection, i.e., screeningfor the product encoded by the genetic marker. Many commonly usedselectable marker genes for plant transformation are well known in thetransformation arts, and include, for example, genes that code forenzymes that metabolically detoxify a selective chemical agent which maybe an antibiotic or an herbicide, or genes that encode an altered targetwhich is insensitive to the inhibitor. A few positive selection methodsare also known in the art.

One commonly used selectable marker gene for plant transformation is theneomycin phosphotransferase II (nptII) gene, isolated from transposonTn5, which when placed under the control of plant regulatory signalsconfers resistance to kanamycin. Fraley, et al., PNAS, 80:4803 (1983).Another commonly used selectable marker gene is the hygromycinphosphotransferase gene which confers resistance to the antibiotichygromycin. Vanden Elzen, et al., Plant Mol. Biol., 5:299 (1985).

Additional selectable marker genes of bacterial origin that conferresistance to antibiotics include gentamycin acetyl transferase,streptomycin phosphotransferase, aminoglycoside-3′-adenyl transferase,the bleomycin resistance determinant. Hayford, et al., Plant Physiol.,86:1216 (1988); Jones, et al., Mol. Gen. Genet., 210:86 (1987); Svab, etal., Plant Mol. Biol., 14:197 (1990); Hille, et al., Plant Mol. Biol.,7:171 (1986). Other selectable marker genes confer resistance toherbicides such as glyphosate, glufosinate, or bromoxynil. Comai, etal., Nature, 317:741-744 (1985); Gordon-Kamm, et al., Plant Cell,2:603-618 (1990); and Stalker, et al., Science, 242:419-423 (1988).

Selectable marker genes for plant transformation that are not ofbacterial origin include, for example, mouse dihydrofolate reductase,plant 5-enolpyruvylshikimate-3-phosphate synthase, and plantacetolactate synthase. Eichholtz, et al., Somatic Cell Mol. Genet.,13:67 (1987); Shah, et al., Science, 233:478 (1986); and Charest, etal., Plant Cell Rep., 8:643 (1990).

Another class of marker genes for plant transformation requiresscreening of presumptively transformed plant cells rather than directgenetic selection of transformed cells for resistance to a toxicsubstance such as an antibiotic. These genes are particularly useful toquantify or visualize the spatial pattern of expression of a gene inspecific tissues and are frequently referred to as reporter genesbecause they can be fused to a gene or gene regulatory sequence for theinvestigation of gene expression. Commonly used genes for screeningpresumptively transformed cells include α-glucuronidase (GUS),α-galactosidase, luciferase and chloramphenicol, acetyltransferase.Jefferson, R. A., Plant Mol. Biol., 5:387 (1987); Teeri, et al., EMBOJ., 8:343 (1989); Koncz, et al., PNAS, 84:131 (1987); and DeBlock, etal., EMBO J., 3:1681 (1984).

In vivo methods for visualizing GUS activity that do not requiredestruction of plant tissues are available. Molecular Probes,Publication 2908, IMAGENE GREEN, pp. 1-4 (1993) and Naleway, et al., J.Cell Biol., 115:151a (1991). However, these in vivo methods forvisualizing GUS activity have not proven useful for recovery oftransformed cells because of low sensitivity, high fluorescentbackgrounds, and limitations associated with the use of luciferase genesas selectable markers.

More recently, a gene encoding Green Fluorescent Protein (GFP) has beenutilized as a marker for gene expression in prokaryotic and eukaryoticcells. Chalfie, et al., Science, 263:802 (1994). GFP and mutants of GFPmay be used as screenable markers.

Expression Vectors for Lettuce Transformation: Promoters

Genes included in expression vectors must be driven by a nucleotidesequence comprising a regulatory element (for example, a promoter).Several types of promoters are now well known in the transformationarts, as are other regulatory elements that can be used alone or incombination with promoters.

As used herein, “promoter” includes reference to a region of DNAupstream from the start of transcription and involved in recognition andbinding of RNA polymerase and other proteins to initiate transcription.A “plant promoter” is a promoter capable of initiating transcription inplant cells. Examples of promoters under developmental control includepromoters that preferentially initiate transcription in certain tissues,such as leaves, roots, seeds, fibers, xylem vessels, tracheids, orsclerenchyma. Such promoters are referred to as “tissue-preferred.”Promoters which initiate transcription only in certain tissue arereferred to as “tissue-specific.” A “cell type” specific promoterprimarily drives expression in certain cell types in one or more organs,for example, vascular cells in roots or leaves. An “inducible” promoteris a promoter which is under environmental control. Examples ofenvironmental conditions that may effect transcription by induciblepromoters include anaerobic conditions or the presence of light.Tissue-specific, tissue-preferred, cell type specific, and induciblepromoters constitute the class of “non-constitutive” promoters. A“constitutive” promoter is a promoter which is active under mostenvironmental conditions.

A. Inducible Promoters:

An inducible promoter is operably linked to a gene for expression inlettuce. Optionally, the inducible promoter is operably linked to anucleotide sequence encoding a signal sequence which is operably linkedto a gene for expression in lettuce. With an inducible promoter, therate of transcription increases in response to an inducing agent.

Any inducible promoter can be used in the instant invention. See Ward,et al., Plant Mol. Biol., 22:361-366 (1993). Exemplary induciblepromoters include, but are not limited to, that from the ACEI systemwhich responds to copper (Meft, et al., PNAS, 90:4567-4571 (1993)); In2gene from maize which responds to benzenesulfonamide herbicide safeners(Hershey, et al., Mol. Gen. Genet., 227:229-237 (1991) and Gatz, et al.,Mol. Gen. Genet., 243:32-38 (1994)) or Tet repressor from Tn10 (Gatz, etal., Mol. Gen. Genet., 227:229-237 (1991)). A particularly preferredinducible promoter is a promoter that responds to an inducing agent towhich plants do not normally respond. An exemplary inducible promoter isthe inducible promoter from a steroid hormone gene, the transcriptionalactivity of which is induced by a glucocorticosteroid hormone. Schena,et al., PNAS, 88:0421 (1991).

B. Constitutive Promoters:

A constitutive promoter is operably linked to a gene for expression inlettuce or the constitutive promoter is operably linked to a nucleotidesequence encoding a signal sequence which is operably linked to a genefor expression in lettuce.

Many different constitutive promoters can be utilized in the instantinvention. Exemplary constitutive promoters include, but are not limitedto, the promoters from plant viruses such as the 35S promoter from CaMV(Odell, et al., Nature, 313:810-812 (1985)) and the promoters from suchgenes as rice actin (McElroy, et al., Plant Cell, 2:163-171 (1990));ubiquitin (Christensen, et al., Plant Mol. Biol., 12:619-632 (1989) andChristensen, et al., Plant Mol. Biol., 18:675-689 (1992)); pEMU (Last,et al., Theor. Appl. Genet., 81:581-588 (1991)); MAS (Velten, et al.,EMBO J., 3:2723-2730 (1984)) and maize H3 histone (Lepetit, et al., Mol.Gen. Genet., 231:276-285 (1992) and Atanassova, et al., Plant J., 2(3):291-300 (1992)). The ALS promoter, Xbal/Ncol fragment 5′ to theBrassica napus ALS3 structural gene (or a nucleotide sequence similarityto said Xbal/Ncol fragment), represents a particularly usefulconstitutive promoter. See PCT Application No. WO 96/30530.

C. Tissue-Specific or Tissue-Preferred Promoters:

A tissue-specific promoter is operably linked to a gene for expressionin lettuce. Optionally, the tissue-specific promoter is operably linkedto a nucleotide sequence encoding a signal sequence which is operablylinked to a gene for expression in lettuce. Plants transformed with agene of interest operably linked to a tissue-specific promoter producethe protein product of the transgene exclusively, or preferentially, ina specific tissue.

Any tissue-specific or tissue-preferred promoter can be utilized in theinstant invention. Exemplary tissue-specific or tissue-preferredpromoters include, but are not limited to, a root-preferred promoter,such as that from the phaseolin gene (Murai, et al., Science, 23:476-482(1983) and Sengupta-Gopalan, et al., PNAS, 82:3320-3324 (1985)); aleaf-specific and light-induced promoter such as that from cab orrubisco (Simpson, et al., EMBO J., 4(11):2723-2729 (1985) and Timko, etal., Nature, 318:579-582 (1985)); an anther-specific promoter such asthat from LAT52 (Twell, et al., Mol. Gen. Genet., 217:240-245 (1989)); apollen-specific promoter such as that from Zml3 (Guerrero, et al., Mol.Gen. Genet., 244:161-168 (1993)) or a microspore-preferred promoter suchas that from apg (Twell, et al., Sex. Plant Reprod., 6:217-224 (1993)).

Signal Sequences for Targeting Proteins to Subcellular Compartments

Transport of protein produced by transgenes to a subcellular compartmentsuch as the chloroplast, vacuole, peroxisome, glyoxysome, cell wall, ormitochondrion, or for secretion into the apoplast, is accomplished bymeans of operably linking the nucleotide sequence encoding a signalsequence to the 5′ and/or 3′ region of a gene encoding the protein ofinterest. Targeting sequences at the 5′ and/or 3′ end of the structuralgene may determine, during protein synthesis and processing, where theencoded protein is ultimately compartmentalized.

The presence of a signal sequence directs a polypeptide to either anintracellular organelle or subcellular compartment or for secretion tothe apoplast. Many signal sequences are known in the art. See, forexample, Becker, et al., Plant Mol. Biol., 20:49 (1992); Close, P. S.,Master's Thesis, Iowa State University (1993); Knox, C., et al.,“Structure and Organization of Two Divergent Alpha-Amylase Genes fromBarley,” Plant Mol. Biol., 9:3-17 (1987); Lerner, et al., PlantPhysiol., 91:124-129 (1989); Fontes, et al., Plant Cell, 3:483-496(1991); Matsuoka, et al., PNAS, 88:834 (1991); Gould, et al., J. Cell.Biol., 108:1657 (1989); Creissen, et al., Plant J., 2:129 (1991);Kalderon, et al., A short amino acid sequence able to specify nuclearlocation, Cell, 39:499-509 (1984); and Steifel, et al., Expression of amaize cell wall hydroxyproline-rich glycoprotein gene in early leaf androot vascular differentiation, Plant Cell, 2:785-793 (1990).

Foreign Protein Genes and Agronomic Genes

With transgenic plants according to the present invention, a foreignprotein can be produced in commercial quantities. Thus, techniques forthe selection and propagation of transformed plants, which are wellunderstood in the art, yield a plurality of transgenic plants which areharvested in a conventional manner, and a foreign protein then can beextracted from a tissue of interest or from total biomass. Proteinextraction from plant biomass can be accomplished by known methods whichare discussed, for example, by Heney and Orr, Anal. Biochem., 114:92-6(1981).

According to a preferred embodiment, the transgenic plant provided forcommercial production of foreign protein is lettuce. In anotherpreferred embodiment, the biomass of interest is seed. For therelatively small number of transgenic plants that show higher levels ofexpression, a genetic map can be generated, primarily via conventionalRFLP, PCR, and SSR analysis, which identifies the approximatechromosomal location of the integrated DNA molecule. For exemplarymethodologies in this regard, see Methods in Plant Molecular Biology andBiotechnology, Glick and Thompson Eds., 269:284, CRC Press, Boca Raton(1993). Map information concerning chromosomal location is useful forproprietary protection of a subject transgenic plant. If unauthorizedpropagation is undertaken and crosses made with other germplasm, the mapof the integration region can be compared to similar maps for suspectplants, to determine if the latter have a common parentage with thesubject plant. Map comparisons would involve hybridizations, RFLP, PCR,SSR, and sequencing, all of which are conventional techniques.

Likewise, by means of the present invention, agronomic genes can beexpressed in transformed plants. More particularly, plants can begenetically engineered to express various phenotypes of agronomicinterest. Exemplary genes implicated in this regard include, but are notlimited to, those categorized below:

A. Genes that Confer Resistance to Pests or Disease and that Encode:

1. Plant disease resistance genes. Plant defenses are often activated byspecific interaction between the product of a disease resistance gene(R) in the plant and the product of a corresponding avirulence (Avr)gene in the pathogen. A plant line can be transformed with a clonedresistance gene to engineer plants that are resistant to specificpathogen strains. See, for example, Jones, et al., Science, 266:789(1994) (cloning of the tomato Cf-9 gene for resistance to Cladosporiumfulvum); Martin, et al., Science, 262:1432 (1993) (tomato Pto gene forresistance to Pseudomonas syringae pv. tomato encodes a protein kinase);and Mindrinos, et al., Cell, 78:1089 (1994) (Arabidopsis RSP2 gene forresistance to Pseudomonas syringae).

2. A Bacillus thuringiensis protein, a derivative thereof, or asynthetic polypeptide modeled thereon. See, for example, Geiser, et al.,Gene, 48:109 (1986), who disclose the cloning and nucleotide sequence ofa Bt δ-endotoxin gene. Moreover, DNA molecules encoding δ-endotoxingenes can be purchased from American Type Culture Collection, Manassas,Va., for example, under ATCC Accession Nos. 40098, 67136, 31995, and31998.

3. A lectin. See, for example, the disclosure by Van Damme, et al.,Plant Mol. Biol., 24:25 (1994), who disclose the nucleotide sequences ofseveral Clivia miniata mannose-binding lectin genes.

4. A vitamin-binding protein such as avidin. See PCT Application No. US93/06487, the contents of which are hereby incorporated by reference.The application teaches the use of avidin and avidin homologues aslarvicides against insect pests.

5. An enzyme inhibitor, for example, a protease or proteinase inhibitor,or an amylase inhibitor. See, for example, Abe, et al., J. Biol. Chem.,262:16793 (1987) (nucleotide sequence of rice cysteine proteinaseinhibitor); Huub, et al., Plant Mol. Biol., 21:985 (1993) (nucleotidesequence of cDNA encoding tobacco proteinase inhibitor I); and Sumitani,et al., Biosci. Biotech. Biochem., 57:1243 (1993) (nucleotide sequenceof Streptomyces nitrosporeus α-amylase inhibitor).

6. An insect-specific hormone or pheromone, such as an ecdysteroid andjuvenile hormone, a variant thereof, a mimetic based thereon, or anantagonist or agonist thereof. See, for example, the disclosure byHammock, et al., Nature, 344:458 (1990), of baculovirus expression ofcloned juvenile hormone esterase, an inactivator of juvenile hormone.

7. An insect-specific peptide or neuropeptide which, upon expression,disrupts the physiology of the affected pest. For example, see thedisclosures of Regan, J. Biol. Chem., 269:9 (1994) (expression cloningyields DNA coding for insect diuretic hormone receptor) and Pratt, etal., Biochem. Biophys. Res. Comm., 163:1243 (1989) (an allostatin isidentified in Diploptera puntata). See also, U.S. Pat. No. 5,266,317 toTomalski, et al., who disclose genes encoding insect-specific, paralyticneurotoxins.

8. An insect-specific venom produced in nature, by a snake, a wasp, etc.For example, see Pang, et al., Gene, 116:165 (1992), for disclosure ofheterologous expression in plants of a gene coding for a scorpioninsectotoxic peptide.

9. An enzyme responsible for a hyper-accumulation of a monoterpene, asesquiterpene, a steroid, hydroxamic acid, a phenylpropanoid derivative,or another non-protein molecule with insecticidal activity.

10. An enzyme involved in the modification, including thepost-translational modification, of a biologically active molecule; forexample, a glycolytic enzyme, a proteolytic enzyme, a lipolytic enzyme,a nuclease, a cyclase, a transaminase, an esterase, a hydrolase, aphosphatase, a kinase, a phosphorylase, a polymerase, an elastase, achitinase, and a glucanase, whether natural or synthetic. See PCTApplication No. WO 93/02197 in the name of Scott, et al., whichdiscloses the nucleotide sequence of a callase gene. DNA molecules whichcontain chitinase-encoding sequences can be obtained, for example, fromthe ATCC under Accession Nos. 39637 and 67152. See also, Kramer, et al.,Insect Biochem. Mol. Biol., 23:691 (1993), who teach the nucleotidesequence of a cDNA encoding tobacco hornworm chitinase, and Kawalleck,et al., Plant Mol. Biol., 21:673 (1993), who provide the nucleotidesequence of the parsley ubi4-2 polyubiquitin gene.

11. A molecule that stimulates signal transduction. For example, see thedisclosure by Botella, et al., Plant Mol. Biol., 24:757 (1994), ofnucleotide sequences for mung bean calmodulin cDNA clones, and Griess,et al., Plant Physiol., 104:1467 (1994), who provide the nucleotidesequence of a maize calmodulin cDNA clone.

12. A hydrophobic moment peptide. See PCT Application No. WO 95/16776(disclosure of peptide derivatives of tachyplesin which inhibit fungalplant pathogens) and PCT Application No. WO 95/18855 (teaches syntheticantimicrobial peptides that confer disease resistance), the respectivecontents of which are hereby incorporated by reference.

13. A membrane permease, a channel former, or a channel blocker. Forexample, see the disclosure of Jaynes, et al., Plant Sci., 89:43 (1993),of heterologous expression of a cecropin-13, lytic peptide analog torender transgenic tobacco plants resistant to Pseudomonas solanacearum.

14. A viral-invasive protein or a complex toxin derived therefrom. Forexample, the accumulation of viral coat proteins in transformed plantcells imparts resistance to viral infection and/or disease developmenteffected by the virus from which the coat protein gene is derived, aswell as by related viruses. See Beachy, et al., Ann. Rev. Phytopathol.,28:451 (1990). Coat protein-mediated resistance has been conferred upontransformed plants against alfalfa mosaic virus, cucumber mosaic virus,tobacco streak virus, potato virus X, potato virus Y, tobacco etchvirus, tobacco rattle virus, and tobacco mosaic virus. Id.

15. An insect-specific antibody or an immunotoxin derived therefrom.Thus, an antibody targeted to a critical metabolic function in theinsect gut would inactivate an affected enzyme, killing the insect. SeeTaylor, et al., Abstract #497, Seventh Int'l Symposium on MolecularPlant-Microbe Interactions, Edinburgh, Scotland (1994) (enzymaticinactivation in transgenic tobacco via production of single-chainantibody fragments).

16. A virus-specific antibody. See, for example, Tavladoraki, et al.,Nature, 366:469 (1993), who show that transgenic plants expressingrecombinant antibody genes are protected from virus attack.

17. A developmental-arrestive protein produced in nature by a pathogenor a parasite. Thus, fungal endo-α-1,4-D-polygalacturonases facilitatefungal colonization and plant nutrient released by solubilizing plantcell wall homo-α-1,4-D-galacturonase. See Lamb, et al., Bio/technology,10:1436 (1992). The cloning and characterization of a gene which encodesa bean endopolygalacturonase-inhibiting protein is described by Toubart,et al., Plant J., 2:367 (1992).

18. A developmental-arrestive protein produced in nature by a plant. Forexample, Logemann, et al., Bio/technology, 10:305 (1992), have shownthat transgenic plants expressing the barley ribosome-inactivating genehave an increased resistance to fungal disease.

19. A lettuce mosaic potyvirus (LMV) coat protein gene introduced intoLactuca sativa in order to increase its resistance to LMV infection. SeeDinant, et al., Mol. Breeding, 3:1, 75-86 (1997).

Any of the above listed disease or pest resistance genes (1-19) can beintroduced into the claimed lettuce cultivar through a variety of meansincluding but not limited to transformation and crossing.

B. Genes that Confer Resistance to an Herbicide:

1. An herbicide that inhibits the growing point or meristem, such as animidazolinone or a sulfonylurea. Exemplary genes in this category codefor mutant ALS and AHAS enzyme as described, for example, by Lee, etal., EMBO J., 7:1241 (1988) and Miki, et al., Theor. Appl. Genet.,80:449 (1990), respectively.

2. Glyphosate (resistance conferred by mutant5-enolpyruvlshikimate-3-phosphate synthase (EPSPS) and aroA genes,respectively) and other phosphono compounds, such as glufosinate(phosphinothricin acetyl transferase (PAT), dicamba and Streptomyceshygroscopicus phosphinothricin-acetyl transferase PAT bar genes), andpyridinoxy or phenoxy proprionic acids and cyclohexones (ACCaseinhibitor-encoding genes). See, for example, U.S. Pat. No. 4,940,835 toShah, et al., which discloses the nucleotide sequence of a form of EPSPSwhich can confer glyphosate resistance. A DNA molecule encoding a mutantaroA gene can be obtained under ATCC Accession No. 39256, and thenucleotide sequence of the mutant gene is disclosed in U.S. Pat. No.4,769,061 to Comai. See also, Umaballava-Mobapathie in TransgenicResearch, 8:1, 33-44 (1999) that discloses Lactuca sativa resistant toglufosinate. European Patent Application No. 0 333 033 to Kumada, etal., and U.S. Pat. No. 4,975,374 to Goodman, et al., disclose nucleotidesequences of glutamine synthetase genes which confer resistance toherbicides, such as L-phosphinothricin. The nucleotide sequence of aphosphinothricin-acetyl-transferase gene is provided in EuropeanApplication No. 0 242 246 to Leemans, et al. DeGreef, et al.,Bio/technology, 7:61 (1989), describe the production of transgenicplants that express chimeric bar genes coding for phosphinothricinacetyl transferase activity. Exemplary of genes conferring resistance tophenoxy proprionic acids and cyclohexones, such as sethoxydim andhaloxyfop, are the Acc1-S1, Acc1-S2, and Acc1-S3 genes described byMarshall, et al., Theor. Appl. Genet., 83:435 (1992).

3. An herbicide that inhibits photosynthesis, such as a triazine (psbAand gs+ genes) and a benzonitrile (nitrilase gene). Przibilla, et al.,Plant Cell, 3:169 (1991), describe the transformation of Chlamydomonaswith plasmids encoding mutant psbA genes. Nucleotide sequences fornitrilase genes are disclosed in U.S. Pat. No. 4,810,648 to Stalker, andDNA molecules containing these genes are available under ATCC AccessionNos. 53435, 67441, and 67442. Cloning and expression of DNA coding for aglutathione S-transferase is described by Hayes, et al., Biochem. J.,285:173 (1992).

4. Acetohydroxy acid synthase, which has been found to make plants thatexpress this enzyme resistant to multiple types of herbicides, has beenintroduced into a variety of plants. See Hattori, et al., Mol. Gen.Genet., 246:419 (1995). Other genes that confer tolerance to herbicidesinclude a gene encoding a chimeric protein of rat cytochrome P4507A1 andyeast NADPH-cytochrome P450 oxidoreductase (Shiota, et al., PlantPhysiol., 106:17 (1994)), genes for glutathione reductase and superoxidedismutase (Aono, et al., Plant Cell Physiol., 36:1687 (1995)), and genesfor various phosphotransferases (Datta, et al., Plant Mol. Biol., 20:619(1992)).

5. Protoporphyrinogen oxidase (protox) is necessary for the productionof chlorophyll, which is necessary for all plant survival. The protoxenzyme serves as the target for a variety of herbicidal compounds. Theseherbicides also inhibit growth of all the different species of plantspresent, causing their total destruction. The development of plantscontaining altered protox activity which are resistant to theseherbicides are described in U.S. Pat. Nos. 6,288,306, 6,282,837,5,767,373, and International Publication WO 01/12825.

Any of the above listed herbicide genes (1-5) can be introduced into theclaimed lettuce cultivar through a variety of means including, but notlimited to, transformation and crossing. C. Genes That Confer orContribute to a Value-Added Trait, such as:

1. Increased iron content of the lettuce, for example, by introducinginto a plant a soybean ferritin gene as described in Goto, et al., ActaHorticulturae., 521, 101-109 (2000).

2. Decreased nitrate content of leaves, for example, by introducing intoa lettuce a gene coding for a nitrate reductase. See, for example,Curtis, et al., Plant Cell Rep., 18:11, 889-896 (1999).

3. Increased sweetness of the lettuce by introducing a gene coding formonellin that elicits a flavor 100,000 times sweeter than sugar on amolar basis. See Penarrubia, et al., Bio/technology, 10:561-564 (1992).

4. Modified fatty acid metabolism, for example, by introducing into aplant an antisense gene of stearyl-ACP desaturase to increase stearicacid content of the plant. See Knultzon, et al., PNAS, 89:2625 (1992).

5. Modified carbohydrate composition effected, for example, byintroducing into plants a gene coding for an enzyme that alters thebranching pattern of starch. See Shiroza, et al., J. Bacteriol., 170:810(1988) (nucleotide sequence of Streptococcus mutantsfructosyltransferase gene); Steinmetz, et al., Mol. Gen. Genet., 20:220(1985) (nucleotide sequence of Bacillus subtilis levansucrase gene);Pen, et al., Bio/technology, 10:292 (1992) (production of transgenicplants that express Bacillus lichenifonnis α-amylase); Elliot, et al.,Plant Mol. Biol., 21:515 (1993) (nucleotide sequences of tomatoinvertase genes); Søgaard, et al., J. Biol. Chem., 268:22480 (1993)(site-directed mutagenesis of barley α-amylase gene); and Fisher, etal., Plant Physiol., 102:1045 (1993) (maize endosperm starch branchingenzyme II). D. Genes that Control Male-Sterility:

1. Introduction of a deacetylase gene under the control of atapetum-specific promoter and with the application of the chemicalN-Ac-PPT. See International Publication WO 01/29237.

2. Introduction of various stamen-specific promoters. See InternationalPublications WO 92/13956 and WO 92/13957.

3. Introduction of the barnase and the barstar genes. See Paul, et al.,Plant Mol. Biol., 19:611-622 (1992).

Methods for Lettuce Transformation

Numerous methods for plant transformation have been developed, includingbiological and physical, plant transformation protocols. See, forexample, Miki, et al., “Procedures for Introducing Foreign DNA intoPlants” in Methods in Plant Molecular Biology and Biotechnology, Glickand Thompson Eds., CRC Press, Inc., Boca Raton, pp. 67-88 (1993). Inaddition, expression vectors and in vitro culture methods for plant cellor tissue transformation and regeneration of plants are available. See,for example, Gruber, et al., “Vectors for Plant Transformation” inMethods in Plant Molecular Biology and Biotechnology, Glick and ThompsonEds., CRC Press, Inc., Boca Raton, pp. 89-119 (1993). A.Agrobacterium-mediated Transformation:

One method for introducing an expression vector into plants is based onthe natural transformation system of Agrobacterium. See, for example,Horsch, et al., Science, 227:1229 (1985); Curtis, et al., Journal ofExperimental Botany, 45:279, 1441-1449 (1994); Tones, et al., Plant CellTissue and Organ Culture, 34:3, 279-285 (1993); and Dinant, et al.,Molecular Breeding, 3:1, 75-86 (1997). A. tumefaciens and A. rhizogenesare plant pathogenic soil bacteria which genetically transform plantcells. The Ti and Ri plasmids of A. tumefaciens and A. rhizogenes,respectively, carry genes responsible for genetic transformation of theplant. See, for example, Kado, C. I., Crit. Rev. Plant Sci., 10:1(1991). Descriptions of Agrobacterium vector systems and methods forAgrobacterium-mediated gene transfer are provided by Gruber, et al.,supra, Miki, et al., supra, and Moloney, et al., Plant Cell Rep., 8:238(1989). See also, U.S. Pat. No. 5,591,616 issued Jan. 7, 1997.

B. Direct Gene Transfer:

Several methods of plant transformation collectively referred to asdirect gene transfer have been developed as an alternative toAgrobacterium-mediated transformation. A generally applicable method ofplant transformation is microproj ectile-mediated transformation whereinDNA is carried on the surface of microprojectiles measuring 1 μm to 4μm. The expression vector is introduced into plant tissues with abiolistic device that accelerates the microprojectiles to speeds of 300m/s to 600 m/s which is sufficient to penetrate plant cell walls andmembranes. Russell, D. R., et al., Plant Cell Rep., 12 (3, January),165-169 (1993); Aragao, F. J. L., et al., Plant Mol. Biol., 20 (2,October), 357-359 (1992); Aragao, F. J. L., et al., Plant Cell Rep., 12(9, July), 483-490 (1993); Aragao, Theor. Appl. Genet., 93:142-150(1996); Kim, J., Minamikawa, T., Plant Sci., 117:131-138 (1996);Sanford, et al., Part. Sci. Technol., 5:27 (1987); Sanford, J. C.,Trends Biotech., 6:299 (1988); Klein, et al., Bio/technology, 6:559-563(1988); Sanford, J. C., Physiol. Plant, 7:206 (1990); Klein, et al.,Bio/technology, 10:268 (1992).

Another method for physical delivery of DNA to plants is sonication oftarget cells. Zhang, et al., Bio/technology, 9:996 (1991).Alternatively, liposome and spheroplast fusion have been used tointroduce expression vectors into plants. Deshayes, et al., EMBO J.,4:2731 (1985) and Christou, et al., PNAS, 84:3962 (1987). Direct uptakeof DNA into protoplasts using CaCl₂ precipitation, polyvinyl alcohol, orpoly-L-ornithine has also been reported. Hain, et al., Mol. Gen. Genet.,199:161 (1985) and Draper, et al., Plant Cell Physiol., 23:451 (1982).Electroporation of protoplasts and whole cells and tissues have alsobeen described. Saker, M., Kuhne, T., Biologia Plantarum, 40(4):507-514(1997/98); Donn, et al., In Abstracts of VIIth International Congress onPlant Cell and Tissue Culture IAPTC, A2-38, p. 53 (1990); D'Halluin, etal., Plant Cell, 4:1495-1505 (1992); and Spencer, et al., Plant Mol.Biol., 24:51-61 (1994). See also Chupean, et al., Bio/technology, 7:5,503-508 (1989).

Additional methods include, but are not limited to, expression vectorsintroduced into plant tissues using a direct gene transfer method, suchas microprojectile-mediated delivery, DNA injection, electroporation,and the like. More preferably, expression vectors are introduced intoplant tissues by using either microprojectile-mediated delivery with abiolistic device or by using Agrobacterium-mediated transformation.Transformed plants obtained with the protoplasm of the invention areintended to be within the scope of this invention.

Following transformation of lettuce target tissues, expression of theabove-described selectable marker genes allows for preferentialselection of transformed cells, tissues and/or plants, usingregeneration and selection methods now well known in the art.

The foregoing methods for transformation would typically be used forproducing a transgenic line. The transgenic line could then be crossedwith another (non-transformed or transformed) line in order to produce anew transgenic lettuce line. Alternatively, a genetic trait which hasbeen engineered into a particular lettuce cultivar using the foregoingtransformation techniques could be introduced into another line usingtraditional backcrossing techniques that are well known in the plantbreeding arts. For example, a backcrossing approach could be used tomove an engineered trait from a public, non-elite inbred line into anelite inbred line, or from an inbred line containing a foreign gene inits genome into an inbred line or lines which do not contain that gene.As used herein, “crossing” can refer to a simple X by Y cross, or theprocess of backcrossing, depending on the context.

Gene Conversions

When the term “lettuce plant” is used in the context of the presentinvention, this also includes any gene conversions of that variety. Theterm “gene converted plant” as used herein refers to those lettuceplants which are developed by backcrossing, genetic engineering, ormutation, wherein essentially all of the desired morphological andphysiological characteristics of a variety are recovered in addition tothe one or more genes transferred into the variety via the backcrossingtechnique, genetic engineering, or mutation. Backcrossing methods can beused with the present invention to improve or introduce a characteristicinto the variety. The term “backcrossing” as used herein refers to therepeated crossing of a hybrid progeny back to the recurrent parent,i.e., backcrossing 1, 2, 3, 4, 5, 6, 7, 8, 9, or more times to therecurrent parent. The parental lettuce plant which contributes the genefor the desired characteristic is termed the “nonrecurrent” or “donorparent.” This terminology refers to the fact that the nonrecurrentparent is used one time in the backcross protocol and therefore does notrecur. The parental lettuce plant to which the gene or genes from thenonrecurrent parent are transferred is known as the recurrent parent asit is used for several rounds in the backcrossing protocol. Poehlman &Sleper (1994) and Fehr (1993). In a typical backcross protocol, theoriginal variety of interest (recurrent parent) is crossed to a secondvariety (nonrecurrent parent) that carries the gene of interest to betransferred. The resulting progeny from this cross are then crossedagain to the recurrent parent and the process is repeated until alettuce plant is obtained wherein essentially all of the desiredmorphological and physiological characteristics of the recurrent parentare recovered in the converted plant, in addition to the transferredgene from the nonrecurrent parent.

The selection of a suitable recurrent parent is an important step for asuccessful backcrossing procedure. The goal of a backcross protocol isto alter or substitute a trait or characteristic in the original line.To accomplish this, a gene of the recurrent cultivar is modified orsubstituted with the desired gene from the nonrecurrent parent, whileretaining essentially all of the rest of the desired genetic, andtherefore the desired physiological and morphological, Palermo of theoriginal line. The choice of the particular nonrecurrent parent willdepend on the purpose of the backcross. One of the major purposes is toadd some commercially desirable, agronomically important trait to theplant. The exact backcrossing protocol will depend on the characteristicor trait being altered to determine an appropriate testing protocol.Although backcrossing methods are simplified when the characteristicbeing transferred is a dominant allele, a recessive allele may also betransferred. In this instance it may be necessary to introduce a test ofthe progeny to determine if the desired characteristic has beensuccessfully transferred.

Many gene traits have been identified that are not regularly selected inthe development of a new line but that can be improved by backcrossingtechniques. Gene traits may or may not be transgenic. Examples of thesetraits include, but are not limited to, male sterility, modified fattyacid metabolism, modified carbohydrate metabolism, herbicide resistance,resistance for bacterial, fungal, or viral disease, insect resistance,enhanced nutritional quality, industrial usage, yield stability, andyield enhancement. These genes are generally inherited through thenucleus. Several of these gene traits are described in U.S. Pat. Nos.5,777,196, 5,948,957, and 5,969,212, the disclosures of which arespecifically hereby incorporated by reference.

Tissue Culture

Further reproduction of the variety can occur by tissue culture andregeneration. Tissue culture of various tissues of lettuce andregeneration of plants therefrom is well known and widely published. Forexample, reference may be had to Teng, et al., HortScience, 27:9,1030-1032 (1992); Teng, et al., HortScience, 28:6, 669-1671 (1993);Zhang, et al., Journal of Genetics and Breeding, 46:3, 287-290 (1992);Webb, et al., Plant Cell Tissue and Organ Culture, 38:1, 77-79 (1994);Curtis, et al., Journal of Experimental Botany, 45:279, 1441-1449(1994); Nagata, et al., Journal for the American Society forHorticultural Science, 125:6, 669-672 (2000); and Ibrahim, et al., PlantCell Tissue and Organ Culture, 28(2), 139-145 (1992). It is clear fromthe literature that the state of the art is such that these methods ofobtaining plants are routinely used and have a very high rate ofsuccess. Thus, another aspect of this invention is to provide cellswhich upon growth and differentiation produce lettuce plants having thephysiological and morphological characteristics of variety Palermo.

As used herein, the term “tissue culture” indicates a compositioncomprising isolated cells of the same or a different type or acollection of such cells organized into parts of a plant. Exemplarytypes of tissue cultures are protoplasts, calli, meristematic cells, andplant cells that can generate tissue culture that are intact in plantsor parts of plants, such as leaves, pollen, embryos, roots, root tips,anthers, pistils, flowers, seeds, petioles, suckers, and the like. Meansfor preparing and maintaining plant tissue culture are well known in theart. By way of example, a tissue culture comprising organs has been usedto produce regenerated plants. U.S. Pat. Nos. 5,959,185, 5,973,234, and5,977,445 describe certain techniques, the disclosures of which areincorporated herein by reference.

Additional Breeding Methods

This invention also is directed to methods for producing a lettuce plantby crossing a first parent lettuce plant with a second parent lettuceplant wherein the first or second parent lettuce plant is a lettuceplant of cultivar Palermo. Further, both first and second parent lettuceplants can come from lettuce cultivar Palermo. Thus, any such methodsusing lettuce cultivar Palermo are part of this invention: selfing,backcrosses, hybrid production, crosses to populations, and the like.All plants produced using lettuce cultivar Palermo as at least oneparent are within the scope of this invention, including those developedfrom cultivars derived from lettuce cultivar Palermo. Advantageously,this lettuce cultivar could be used in crosses with other, different,lettuce plants to produce the first generation (F₁) lettuce hybrid seedsand plants with superior characteristics. The cultivar of the inventioncan also be used for transformation where exogenous genes are introducedand expressed by the cultivar of the invention. Genetic variants createdeither through traditional breeding methods using lettuce cultivarPalermo or through transformation of cultivar Palermo by any of a numberof protocols known to those of skill in the art are intended to bewithin the scope of this invention.

The following describes breeding methods that may be used with lettucecultivar Palermo in the development of further lettuce plants. One suchembodiment is a method for developing cultivar Palermo progeny lettuceplants in a lettuce plant breeding program comprising: obtaining thelettuce plant, or a part thereof, of cultivar Palermo, utilizing saidplant or plant part as a source of breeding material, and selecting alettuce cultivar Palermo progeny plant with molecular markers in commonwith cultivar Palermo and/or with morphological and/or physiologicalcharacteristics selected from the characteristics listed in Table 1.Breeding steps that may be used in the lettuce plant breeding programinclude pedigree breeding, backcrossing, mutation breeding, andrecurrent selection. In conjunction with these steps, techniques such asRFLP-enhanced selection, genetic marker enhanced selection (for example,SSR markers), and the making of double haploids may be utilized.

Another method involves producing a population of lettuce cultivarPalermo progeny lettuce plants, comprising crossing cultivar Palermowith another lettuce plant, thereby producing a population of lettuceplants, which, on average, derive 50% of their alleles from lettucecultivar Palermo. A plant of this population may be selected andrepeatedly selfed or sibbed with a lettuce cultivar resulting from thesesuccessive filial generations. One embodiment of this invention is thelettuce cultivar produced by this method and that has obtained at least50% of its alleles from lettuce cultivar Palermo.

One of ordinary skill in the art of plant breeding would know how toevaluate the traits of two plant varieties to determine if there is nosignificant difference between the two traits expressed by thosevarieties. For example, see Fehr and Walt, Principles of CultivarDevelopment, pp. 261-286 (1987). Thus the invention includes lettucecultivar Palermo progeny lettuce plants comprising a combination of atleast two cultivar Palermo traits selected from the group consisting ofthose listed in Table 1, so that said progeny lettuce plant is notsignificantly different for said traits than lettuce cultivar Palermo asdetermined at the 5% significance level when grown in the sameenvironmental conditions. Using techniques described herein, molecularmarkers may be used to identify said progeny plant as a lettuce cultivarPalermo progeny plant. Mean trait values may be used to determinewhether trait differences are significant, and preferably the traits aremeasured on plants grown under the same environmental conditions. Oncesuch a variety is developed, its value is substantial since it isimportant to advance the germplasm base as a whole in order to maintainor improve traits such as yield, disease resistance, pest resistance,and plant performance in extreme environmental conditions.

Progeny of lettuce cultivar Palermo may also be characterized throughtheir filial relationship with lettuce cultivar Palermo, as for example,being within a certain number of breeding crosses of lettuce cultivarPalermo. A breeding cross is a cross made to introduce new genetics intothe progeny, and is distinguished from a cross, such as a self or a sibcross, made to select among existing genetic alleles. The lower thenumber of breeding crosses in the pedigree, the closer the relationshipbetween lettuce cultivar Palermo and its progeny. For example, progenyproduced by the methods described herein may be within 1, 2, 3, 4, or 5breeding crosses of lettuce cultivar Palermo.

As used herein, the term “plant” includes plant cells, plantprotoplasts, plant cell tissue cultures from which lettuce plants can beregenerated, plant calli, plant clumps, and plant cells that are intactin plants or parts of plants, such as leaves, pollen, embryos,cotyledons, hypocotyl, roots, root tips, anthers, pistils, flowers,ovules, seeds, stems, and the like.

TABLES

Table 2 below compares some of the characteristics of green leaf lettucecultivar Palermo with a similar commercial green leaf lettuce cultivar,‘Bergam's Green’ (US Plant Variety Protection certificate #200500262)from a trial planted in August 2013 and harvested in October 2013 inChualar, Calif. Table 2, column 1 lists the plant number, column 2 liststhe height in inches for Bergam's Green, column 3 lists the height ininches for Palermo, column 4 lists the weight in ounces for Bergam'sGreen, column 5 lists the weight in ounces for Palermo, column 6 liststhe frame diameter in inches for Bergam's Green, column 7 lists theframe diameter in inches for Palermo, column 8 lists the core length ininches for Bergam's Green, column 9 lists the core length in inches forPalermo, column 10 lists the RHS leaf color for Bergam's Green, andcolumn 11 lists the RHS leaf color for Palermo.

TABLE 2 Height (in.) Weight (oz.) Frame diameter (in.) Bergam's Bergam'sBergam's # Green Palermo Green Palermo Green Palermo 1 11 10 12.6 14.914 12 2 11 9 16.4 15.1 14 12 3 11.5 10 13.9 15.5 13.5 12 4 12 11 15.314.1 13 12 5 10.5 10 16.4 12.9 13 12 6 10.5 10 17.8 12.5 14.5 13 7 10 1017.1 12.8 13.5 12 8 10 10.5 18.4 13.4 13 12 9 10 9.5 18.8 13.1 16 13 1011 9.5 17.5 13.2 13 12 11 11 9 16.4 13.5 13 12 12 12 9 14.9 14.1 15 11.513 11 9.5 18.4 14.5 14 12 14 10.5 10.5 14.7 15 13 12.5 15 10.5 10 2115.5 15 12 16 10.5 10 18.6 14.5 13 12 17 11 10 11.2 13.9 14 13 18 11 921 13.6 16 12 Max 12 11 21 15.5 16 13 Min 10 9 11.2 12.5 13 11.5 Mean10.8333333 9.8055555 16.68888889 14.0055555 13.91666667 12.1666666 Std0.59408852 0.5723760 2.625192181 0.94462704 1.018216434 0.42008402 Dev Ttest 7.31E−06 2.57E−04 9.56E−08 Core length(in.) RHS color Bergam'sBergam's # Green Palermo Green Palermo 1 1 1 146C 146C 2 1.75 1 146C146C 3 1 1 146C 146C 4 1.5 1.5 146C 146C 5 2 1.5 146C 146C 6 2 1 146C146C 7 2 1 146C 146C 8 2 1 146C 146C 9 2 1.5 146C 146C 10 1.5 1.75 146C146C 11 2 1.5 146C 146C 12 1.5 1.5 146C 146C 13 1.5 1 146C 146C 14 2 1146C 146C 15 2 1.5 146C 146C 16 2 1.5 146C 146C 17 1.5 1 146C 146C 18 21.5 146C 146C Max 2 1.75 Min 1 1 Mean 1.736111111 1.26388888 Std0.348021955 0.27749168 Dev T test 7.54E−05

Table 3 shows a comparison of seed color of Palermo compared to the seedcolors of the most common commercial green leaf lettuce varieties. TheRHS color measurements in Table 3 were taken on varieties that were allproduced under the same conditions in 2012 in Corcoran, Calif. Table 3,column 1 shows the variety name, column 2 shows the seed owner company,column 3 shows the seed color and column 4 shows the RHS colordesignation. As shown in Table 3, RHS color designations RHS 199A-Cinclude RHS 199A, RHS 199B and RHS 199C.

TABLE 3 Variety Company Seed Color RHS Color Palermo Vanguard Tan 199A-CCielo Verde Vanguard Tan 199A-C Bergam's Green Enza Zaden Black 200A BigStar Central White 156A Valley Kodiak Orsetti Black 200A North StarParagon Black 200A ProGreen 76 Syngenta Black Scottsdale Orsetti BlackTehama Paragon Black 200A Tropicana Enza Black Two Star Orsetti BlackUnisun Orsetti Black Ventana Paragon Black 200A

As shown in Table 3, Vanguard lettuce varieties Palermo and Cielo Verdehave tan seed color, whereas all other commercial green leaf lettucevarieties have black or white seed color.

Table 4 shows a comparison of length, width, and length to width ratioof the 4^(th) true leaf index of lettuce cultivar Palermo versuscommercial lettuce variety Bergam's Green from a trial grown in Salinas,Calif. in 2013.

TABLE 4 Palermo Bergam's Green Bergam's Length Width Length WidthPalermo Green Sample (cm) (cm) (cm) (cm) L/W × 10 L/W × 10 1 5.5 3.25 85 16.92307692 16 2 5.75 3.5 7 4 16.42857143 17.5 3 6 4.5 6.5 413.33333333 16.25 4 5.5 4 7 4.5 13.75 15.55555556 5 7 4.5 7 5.515.55555556 12.72727273 6 7 4.5 7 5.5 15.55555556 12.72727273 7 6 4 7 515 14 8 6.5 3.5 7.5 5 18.57142857 15 9 6 4 7 4 15 17.5 10 6.25 4 9.5 5.515.625 17.27272727 11 7 4.5 7 4.5 15.55555556 15.55555556 12 6.5 4.5 7.55 14.44444444 15 Max 18.57142857 17.5 Min 13.33333333 12.72727273 Mean15.48 15.42 Std Dev 1.40 1.65 Ttest 0.93

As shown in Table 4, lettuce cultivar Palermo has a larger length towidth ratio than commercial lettuce variety Bergam's Green.

The use of the terms “a,” “an,” and “the,” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. Forexample, if the range 10-15 is disclosed, then 11, 12, 13, and 14 arealso disclosed. All methods described herein can be performed in anysuitable order unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention unless otherwise claimed. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the invention.

DEPOSIT INFORMATION

A deposit of the Vanguard Seed, Inc. proprietary lettuce cultivarPalermo containing mutant allele VSTMA1 which confers tan seed colordisclosed above and recited in the appended claims has been made withthe American Type Culture Collection (ATCC), 10801 University Boulevard,Manassas, Va. 20110. The date of deposit was Oct. 23, 2013. The depositof 2,500 seeds was taken from the same deposit maintained by VanguardSeed, Inc. since prior to the filing date of this application. Allrestrictions will be irrevocably removed upon granting of a patent, andthe deposit is intended to meet all of the requirements of 37 C.F.R.§§1.801-1.809. The ATCC Accession Number is PTA-120671. The deposit willbe maintained in the depository for a period of thirty years, or fiveyears after the last request, or for the enforceable life of the patent,whichever is longer, and will be replaced as necessary during thatperiod.

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions, and sub-combinations thereof. It is thereforeintended that the following appended claims and claims hereafterintroduced are interpreted to include all such modifications,permutations, additions, and sub-combinations as are within their truespirit and scope.

What is claimed is:
 1. A seed of lettuce cultivar Palermo, wherein arepresentative sample seed of said cultivar was deposited under ATCCAccession No. PTA-120671.
 2. A lettuce plant, or a part thereof,produced by growing the seed of claim
 1. 3. A tissue culture producedfrom protoplasts or cells from the plant of claim 2, wherein said cellsor protoplasts are produced from a plant part selected from the groupconsisting of leaf, pollen, embryo, cotyledon, hypocotyl, meristematiccell root, root tip, pistil, anther, ovule, flower, shoot, stem, seed,and petiole.
 4. A lettuce plant regenerated from the tissue culture ofclaim 3, wherein the plant has all of the morphological andphysiological characteristics of cultivar Palermo.
 5. A method forproducing a lettuce seed, said method comprising crossing two lettuceplants and harvesting the resultant lettuce seed, wherein at least onelettuce plant is the lettuce plant of claim
 2. 6. A lettuce seedproduced by the method of claim
 5. 7. A lettuce plant, or a partthereof, produced by growing said seed of claim
 6. 8. The method ofclaim 5, wherein one of said lettuce plants is lettuce cultivar Palermoand the other is transgenic.
 9. A method of producing a male sterilelettuce plant, wherein the method comprises introducing a nucleic acidmolecule that confers male sterility into the lettuce plant of claim 2.10. A male sterile lettuce plant produced by the method of claim
 9. 11.A method of producing an herbicide resistant lettuce plant, wherein saidmethod comprises introducing a gene conferring herbicide resistance intothe plant of claim 2, wherein the herbicide resistance is selected fromthe group consisting of glyphosate, sulfonylurea, imidazolinone,dicamba, glufosinate, phenoxy proprionic acid, L-phosphinothricin,cyclohexone, cyclohexanedione, triazine, and benzonitrile.
 12. Anherbicide resistant lettuce plant produced by the method of claim 11.13. A method of producing a pest or insect resistant lettuce plant,wherein said method comprises introducing a gene conferring pest orinsect resistance into the plant of claim
 2. 14. A pest or insectresistant lettuce plant produced by the method of claim
 13. 15. Thelettuce plant of claim 14, wherein the gene encodes a Bacillusthuringiensis endotoxin.
 16. A method of producing a disease resistantlettuce plant, wherein said method comprises introducing a geneconferring disease resistance into the plant of claim
 2. 17. A diseaseresistant lettuce plant produced by the method of claim
 16. 18. A methodof producing a lettuce plant with a value-added trait, wherein saidmethod comprises introducing a gene conferring a value-added trait intothe plant of claim 2, where said gene encodes a protein selected fromthe group consisting of a ferritin, a nitrate reductase, and a monellin.19. A lettuce plant with a value-added trait produced by the method ofclaim
 18. 20. A method of introducing a desired trait into lettucecultivar Palermo wherein the method comprises: (a) crossing a Palermoplant, wherein a representative sample of seed was deposited under ATCCAccession No. PTA-120671, with a plant of another lettuce cultivar thatcomprises a desired trait, wherein the desired trait is selected fromthe group consisting of male sterility, herbicide resistance, insect orpest resistance, modified bolting and resistance to bacterial disease,fungal disease and viral disease; (b) selecting one or more progenyplants that have the desired trait; (c) backcrossing the selectedprogeny plants with lettuce cultivar Palermo plants to produce backcrossprogeny plants; (d) selecting for backcross progeny plants that have thedesired trait; and (e) repeating steps (c) and (d) two or more times insuccession to produce selected third or higher backcross progeny plantsthat comprise the desired trait.
 21. A lettuce plant produced by themethod of claim 20, wherein the plant has the desired trait andotherwise all of the physiological and morphological characteristics oflettuce cultivar Palermo.
 22. The lettuce plant of claim 21, wherein thedesired trait is herbicide resistance and the resistance is conferred toan herbicide selected from the group consisting of glyphosate,sulfonylurea, imidazolinone, dicamba, glufosinate, phenoxy proprionicacid, L-phosphinothricin, cyclohexone, cyclohexanedione, triazine, andbenzonitrile.
 23. The lettuce plant of claim 21, wherein the desiredtrait is insect or pest resistance and the insect or pest resistance isconferred by a transgene encoding a Bacillus thuringiensis endotoxin.